Abrading implement

ABSTRACT

A unique abrasive disk unit includes a piece of vulcanizable rubber sandwiched between a single abrasive coated ply and a backing disk of fiber material. A stud or fitting is installed centrally within the backing disc and is adapted to be removably secured to a mandrel. The components are assembled in a mold, and the rubber is vulcanized by the application of heat and pressure to form an integral unit having strong flexural properties and a high resistance to deterioration from frictional heat.

United States Patent Field 51 Apr. 4, 1972 [54] ABRADING IMPLEMENT [72]Inventor: Albert Field, c/o Field Abrasive Manf. Co., lnc., 1303 StanleyAvenue, Dayton, Ohio 45404 [22] Filed: Mar. 20, 1970 [21] Appl.No.:21,358

[52] US. Cl ..51/358, 51/297, 51/299 [51] Int. Cl ..B24d 13/14 [58]Field oiSearch ..5l/358,376378, 51/407, 297, 299

[56] References Cited UNITED STATES PATENTS Matouka ..51/358 X 2,950,5848/1960 Welch ..51/378 3,082,582 3/1963 .leske ..5l/407X PrimaryExaminer-Donald G. Kelly Attorney-Marechal, Biebel, French & Bugg [57]ABSTRACT A unique abrasive disk unit includes a piece of vulcanizablerubber sandwiched between a single abrasive coated ply and a backingdisk of fiber material. A stud or fitting is installed centrally withinthe backing disc and is adapted to be removably secured to a mandrel.The components are assembled in a mold, and the rubber is vulcanized bythe application of heat and pressure to form an integral unit havingstrong flexural properties and a high resistance to deterioration fromfrictional heat.

7 Claims, 4 Drawing Figures Patented April 4, 1%72 IN VE/V 706 FIG FIG-lq;

ALBERT FIELD WWMiW A TTOR/VE Y5 ABRADING IMPLEMENT BACKGROUND OF THEINVENTION In abrading implements of the type which employ a singleabrasive-coated cloth or paper ply, the ply is usually bonded to aflexible metal or plastic backing with a relatively thin coating ofadhesive material or the like. Commonly, the backing is provided with ametal fitting for connecting the disk to the working head of themandrel. Such abrading implements are used for de-burring dies, metalpatterns, welding spots and the like, and are usually flexible so thatthey may be applied to a curved working surface.

One problem with such an arrangement is that the frictional dragimparted through the workpiece creates a high heat of friction which,after a period of time, softens the adhesive material and weakens thebond between the ply and the backing. Often the bonds are deterioratedto the point that the ply will begin to slip relative to the backing andeventually be completely separated from it.

Another problem is that adhesive materials form relatively rigid bondswhich have very little elasticity. When the abrasive ply is compressedagainst a curved workpiece, the bending creates a stretching force atthe point of flexure, and the adhesives do not have the elasticity andheat resistance to withstand the high frictional heat. As a result, theply often separates from the backing before it has been put to completeuse.

The methods for assembling adhesively bonded disk units usually includethe steps of applying the adhesive material to the interface between theabrasive ply and backing, clamping the ply and backing together, andallowing the adhesive to dry. While such processes are relatively simpleand straightforward, they do not produce units which have high flexuralstrength and high resistance to frictional heat.

SUMMARY OF THE INVENTION The present invention is directed to animproved abrading implement and includes a new form of abrasive diskunit and a 1 new method of assemblying the same. In general, arelatively thick pad of rubbery material is disposed between theabrasive ply and the backing and positively bonds them into an integralunit upon the application of heat and pressure.

In accordance with a preferred embodiment of the invention, a piece ofvulcanizable rubber is sandwiched between the abrasive ply and thebacking disk and is vulcanized by applying heat. A metal stud or fittingis installed centrally within the backing disk and is riveted over ontothe backing surface. The resulting rivet portion is incorporated intothe unit while the rubber is being vulcanized. A threaded end on thefitting extends from the backing disk and is received in an internallythreaded bore in the working head of the mandrel.

The improved process includes the steps of installing the components ina mold, heating the mold to about 400 F., and applying pressure to thecomponents to spread the rubber over the adjacent surfaces of theabrasive ply and the backing disk. The rubber is allowed to fill theminute voids in the fiber backing and in the cloth ply for a period oftime, and is then pennitted to cool. The process produces an integralabrasive disk unit which has strong and flexible bonds which are highlyresistant to deterioration from frictional heat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view, partly insection, showing the preferred embodiment of the invention;

FIG. 2 is an exploded perspective view, partly in fragmentary section,showing the parts embodied in the preferred embodiment of the presentinvention;

FIG. 3 is a view of the parts of the abrasive disk unit assembled in arepresentative mold, and showing a forming die disposed above the parts;and

FIG. 4 is a view of the parts of the abrasive disk unit afte they havebeen formed into an integral unit by heating the mold and applyingpressure through the die.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1,the abrading implement 10 of the present invention includes a mandrel l1and an abrasive disk unit 12. The mandrel 11 is provided with arotatable arbor or shank 13 which is adapted to be attached to the chuckof a hand drill or some other source of power for rotating theimplement. One end of the shank 13 is provided with an integral workinghead 14, and the end face 15 thereof has a conical recess 16 terminatingin an internally threaded bore 18. The

end face 15 is preferably fiat for engagement with the bottom of theabrasive disk unit 12.

The unit 12 includes a single ply 20 of adhesive coated fabric or paperhaving an uninterrupted surface, a backing disk 22 having a center hole23 and preferably formed of a fibrous material, such as fiberboard, anda metal stud 25 with external threads on one end for threading into themandrel bore 18. The stud 25 is inserted through the center hole 23until the backing 22 is flush with the central flange 26, and itssmaller end is riveted over at 28 upon the adjacent surface to clamp thedisk 22 tightly against the flange 26.

In accordance with the present invention, a piece of vulcanizable rubber30 is sandwiched between the adhesive ply 20 and the fiber backing disk22. Preferably, the piece of rubber 30 is made from crude rubber whichhas been kneaded and thoroughly mixed with vulcanizing ingredients andformed into a sheet which may be cut into squares or the like. Somevulcanizing ingredients which are commonly used are: sulfur orsulfur-bearing materials, or combinations of these with selenium ortellurium, guinoid structures, and dinitrobenene. vulcanizable syntheticrubber, which may utilize other vulcanizing ingredients, can be used aswell.

The method of assembling the abrasive disk unit 12 includes the step ofassembling the parts in a suitable mold 32. Referring to FIGS. 3 and 4,this may be done by placing the adhesive ply 20 into the bottom of themold so that the cloth backing is exposed, placing the piece ofvulcanizable rubber 30 on the cloth backing, and then placing the fiberbacking 22 and installed metal fitting 25 on top of the rubber. As shownin FIG. 3, the rivet portion 28 protruding through the fiber backing 22will rest on the rubber 30 and space the backing above the rubber.

The mold is then heated to a temperature which is sufficient tovulcanize the rubber. The vulcanizing temperature will of course dependupon the mass of the rubber, the type of rubber used, and the method ofheating. Usually, crude rubber can be vulcanized by heating at 200 to400 F. for varying periods of time. Since the abrasive disk unit 12 isformed simultaneously with the vulcanizing process, the vulcanizationmay be carried out by using heat alone, or by using heat combined withpressure.

In accordance with the preferred embodiment of the invention, pressureis used to form the product simultaneously with the vulcanizationprocess. Once the rubber 30 has been heated to its vulcanizingtemperature, a forming die 34 is brought down to engage the exposedsurface of the fiber backing 22 (FIG. 4). Sufficient pressure is exertedto embed the rivet portion 28 in the softened rubber and to spread therubber over the cloth backing of the adhesive ply 20 and the fiberbacking 22. The pressure is held for a period of time to permit therubber to fill into the minute voids in the cloth backing and the fiberbacking. It has been found that a pressure of p.s.i. applied for aperiod of approximately 8 minutes at 400 F. will satisfactorilyvulcanize a 2 inch by 2 inch and one-fourth inch thick square of rubberinto an integral disk unit having an overall diameter of 3 inches andwith a disk 22 about 2 inches in diameter. For purposes of economy andappearance, the mold 34 is preferably constructed with a frusto-conicalconfiguration so that the rubber will flow and form a smoothcircumferential surface 36 extending from the radial extremity of thefiber backing 22 to the radial extremity of the abrasive ply 20.

From the drawing and the above description, it is apparent that certainadvantages and features are provided by the present invention. Forexample, during the vulcanization process the rubber will penetrate intominute voids in the fiber backing 22 and in the cloth ply 20 and, whencured will fonn a multiplicity of strong and flexible bonds between therubber and the adjacent surfaces of the backing 22 and the ply 20.Moreover, the rivet portion 28 is embedded and bonded into therelatively thick rubber layer. The vulcanization process creates bondswhich will not deteriorate under the high temperature generated byfrictional drag.

Furthermore, when the rubber is vulcanized it maintains its elasticitywhile its plasticity is reduced. The rubber 30 will therefore permit theperipheral portion of the unit 12 to bend against a curved workingsurface and at the same time retain its substantially increased bondingcharacteristics. The elastic bonds will therefore bend with the unit andremain substantially unaffected by high frictional temperatures. At thesame time, the relatively stiff fiber disk 22 adequately stiffens theunit as a whole.

Additionally, the vulcanization process of the present inventionincorporates all parts in an integral product without requiring the useof adhesive. The process is relatively simple to perform, requiringsimple molds, and produces a substantially improved product which hasstrong flexural properties and a high resistance to deterioration fromfrictional heat.

While the process and product herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to this precise process and product, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. An abrading implement comprising:

a. an abrasive disk including a backing member having a plurality ofminute voids defined therein,

b. a backing disk of fibrous material having a plurality of minute voidsdefined therein,

c. a stud attached to said backing disk and having portions projectingthrough said backing disk,

d. a molded, vulcanized material interposed between said backing memberof said abrasive disk and said backing disk,

e. portions of said vulcanized material filling said voids in both saidbacking member and said backing disk and forming an integral flexibleunit of said backing member, said stud and said vulcanized material.

2. An abrading implement as defined in claim 1 wherein said studincludes an integral flange for receiving one side of the backing diskflush thereagainst and integral rivet tabs turned over upon the otherside of said disk and embedded in said vulcanized material.

3. An abrading implement as defined in claim I wherein said backingmember of said abrasive disk and said backing disk each comprise afibrous material.

4. An abrading implement as defined in claim 1 wherein said backing diskis of substantially smaller diameter than said ply, and said rubberymaterial includes a frusto-conical portion underlying the portion ofsaid ply lying outwardly of said disk.

5. A process of making an abrading element comprising:

a. securing a stud to a fibrous backing disk having a plurality ofminute voids defined therein,

b. placing an abrasive disk including a backing member hav- 1 ing aplurality of minute voids defined therein in a mold,

c. positioning a layer of vulcanizable material in said mold in contactwith said backing member,

d. positioning said fibrous backing disk on said layer of vulcanizablematerial,

e. subjecting the assembly of said backing disk, said backing member andsaid vulcanizable material to sufficient heat to cause said vulcanizablematerial to flow into said voids in said backing disk and said backingmember and vu lcanize said backing member, said backing dlSk and said

1. An abrading implement comprising: a. an abrasive disk including a backing member having a plurality of minute voids defined therein, b. a backing disk of fibrous material having a plurality of minute voids defined therein, c. a stud attached to said backing disk and having portions projecting through said backing disk, d. a molded, vulcanized material interposed between said backing member of said abrasive disk and said backing disk, e. portions of said vulcanized material filling said voids in both said backing member and said backing disk and forming an integral flexible unit of said backing member, said stud and said vulcanized material.
 2. An abrading implement as defined in claim 1 wherein said stud includes an integral flange for receiving one side of the backing disk flush thereagainst and integral rivet tabs turned over upon the other side of said disk and embedded in said vulcanized material.
 3. An abrading implement as defined in claim 1 wherein said backing member of said abrasiVe disk and said backing disk each comprise a fibrous material.
 4. An abrading implement as defined in claim 1 wherein said backing disk is of substantially smaller diameter than said ply, and said rubbery material includes a frusto-conical portion underlying the portion of said ply lying outwardly of said disk.
 5. A process of making an abrading element comprising: a. securing a stud to a fibrous backing disk having a plurality of minute voids defined therein, b. placing an abrasive disk including a backing member having a plurality of minute voids defined therein in a mold, c. positioning a layer of vulcanizable material in said mold in contact with said backing member, d. positioning said fibrous backing disk on said layer of vulcanizable material, e. subjecting the assembly of said backing disk, said backing member and said vulcanizable material to sufficient heat to cause said vulcanizable material to flow into said voids in said backing disk and said backing member and vulcanize said backing member, said backing disk and said material into an integral unit.
 6. The process of claim 5 further comprising: a. applying pressure to said assembly during heating thereof.
 7. A process as defined in claim 6 wherein said stud includes a rivet portion turned over on the surface of said backing disk adjacent said rubber, and sufficient pressure is applied to embed said disk and rivet portion in said rubber. 